Magnetic storage systems that make use of a magnetic head slider assembly are known and described, for example, in U.S. Pat. No. 5,062,017 to Storm et al., assigned to the assignee of the present invention and incorporated herein by reference. The magnetic head slider assembly includes a load beam, a slider, and a gimbal for attaching the slider to the load beam. The slider also includes a transducer for recording and retrieving information from the rotating magnetic disc as the slider is positioned proximate selected locations on the disc by an actuator.
The actuator includes a positioning arm. The slider assembly is mounted on the positioning arm. For the case of a rotary actuator, the positioning arm pivots about a pivot axis for positioning the slider assembly at any point along an arc extending from an inner radius to an outer radius of the disc surface. In the case of a linear actuator, the positioning arm moves in a linear direction to position the slider assembly at any point along a line extending from an inner radius to an outer radius of the disc surface.
The magnetic disc has a polished surface so that rotation of the magnetic disc causes movement of air relative to the slider producing a hydrodynamic lifting force or air bearing. This air bearing supports the slider proximate the rotating magnetic disc. The gimbal mounting between the slider and the load beam allows the slider to pitch and roll to more closely follow the topography of the disc surface. In this manner, the spacing variation between the transducer and disc surface can be maintained more closely.
To maximize the capacity of the disc storage device, the disc space should be efficiently utilized, however, portions of the disc are not suitable for data storage and retrieval resulting in inefficient utilization of disc space. A landing zone portion if often located toward an inner radius of the disc, referred to as an "inner flyable radius", is not suitable for data storage and retrieval. The landing zone portion is found in disc storage systems in which the slider engages the disc surface during starting and stopping which are frequently referred to as "contact start/stop" systems (CSS). When the disc storage device is powered down, the slider assembly lands or is in contact with the landing zone portion of the disc. To minimize torque on the disc spindle motor, thereby allowing the use of smaller, less expensive motors, the innermost disc surface or disc surface adjacent an "inner flyable radius" is used as the landing zone. The disc surface in the landing zone is damaged by slider contract during landings and takeoffs, thereby affecting the reliability of storage and retrieval of information. For these reasons, the landing zone portion of the disc is not suitable for data storage and retrieval resulting in disc inefficiency.
Another constraint on the utilization of the disc surface is the result of an offset frequently found between the outer edge of the air bearing surface and the transducer preventing the transducer from being positioned at the "outer flyable radius" of the disc surface. The outer flyable radius is that radius specified by the manufacturer over which the air bearing surface of the slider can fly without deleterious effects. Because of this offset the outermost position of the transducer or outermost radius of the recording zone is less than the outer flyable radius resulting a portion of the disc which is not accessible for data storage and retrieval. For this reason, a portion of the disc is not used for data storage and retrieval resulting in disc inefficiency.
In addition to efficient utilization of disc space to maximize data storage capacity, the disc storage device should be reliable. One factor which effects the reliability of the disc storage device is the susceptibility of the slider to collect contamination as it flies over the disc surface. Frequently, individual portions of contamination which by themselves may not be disruptive to the slider but when collected by the slider these individual pieces of contamination unite to form a larger contaminant. This larger contaminant, if dislodged from the slider, may then pass through the air bearing or space between the air bearing surface and the disc surface thereby scratching or damaging either the slider or the disc surface as the contaminant is passed. Furthermore, the passing of contamination through the air bearing disrupts the spacing between the slider and the disc surface. This disruption in the spacing may cause gradual damage to the disc surface or result in catastrophic failure known as "head crash." The gradual damage to the disc surface results from continual impacts between the transducer and the contaminant producing slight contacts with the disc surface which eventually can result in head crash.
There is a present need for air bearing sliders that make efficient utilization of the disc space between the inner flyable radius and the outer flyable radius. This air bearing slider should be designed to help prevent the collection of contaminants which can affect the reliability of the disc storage device. In addition, this air bearing slider should be symmetrical so that the same slider design may be used for either the top surface or bottom surface of the disc. The air bearing slider should be capable of lifting off quickly from the disc surface during disc start-up and fly with a high fly slope thereby reducing friction and wear. The air bearing slider should be insensitive to external forces and be capable of providing the desired fly height versus disc radius relationship. In addition, this air bearing slider should be well suited to the adhesive bonding process used to affix the flexure (or gimbal) to the slider body. Furthermore, this air bearing slider should be well suited to fly testing for easily and quickly determining the head disc separation. Finally, this air bearing slider should have a relatively simple geometry so that it can be easily simulated to determine performance characteristics.